Protective device with improved surge protection

ABSTRACT

The present invention is directed to an electrical wiring protection device that includes a housing assembly having a plurality of line terminals and a plurality of load terminals. A fault detection circuit is coupled to at least one of the plurality of line terminals and configured to generate a fault detection signal in response to detecting at least one fault condition in the electrical distribution system. A circuit interrupter is coupled to the fault detection circuit, The circuit interrupter is configured to couple the plurality of line terminals to the plurality of load terminals to form a conductive electrical path in a reset state, and decouple the plurality of line terminals from the plurality of load terminals in response to a fault detection signal in a tripped state. A voltage transient suppression circuit is coupled to at least one of the plurality of line terminals. The voltage transient suppression circuit is configured to generate a signal simulating the at least one fault condition in the event of failure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to electrical wiring devices,and particularly to protective wiring devices.

2. Technical Background

Electrical distribution systems that provide power to structures such asresidences, commercial buildings or other such facilities typicallyinclude one or more breaker panels coupled to a source of AC power. Ofcourse, the breaker panel distributes AC power to one or more branchelectric circuits installed in the structure. The electric circuits maytypically include one or more receptacle outlets and may furthertransmit AC power to one or more electrically powered devices, commonlyreferred to in the art as load circuits. The receptacle outlets providepower to user-accessible loads that include a power cord and plug, theplug being insertable into the receptacle outlet. However, certain typesof faults have been known to occur in various portions of the electricaldistribution systems. Accordingly, electric circuit protection devicesmay be disposed throughout the distribution system, i.e., in the breakerpanel and in protective devices having receptacle outlets. Protectivedevices may also be installed in the electrical load itself.

Both receptacle wiring devices and electric circuit protective wiringdevices may be disposed in an electrically non-conductive housing. Thehousing includes electrical terminals that are electrically insulatedfrom each other. Line terminals couple the wiring device to conductorsthat provides electrical power from the electrical distribution system.Load terminals are coupled to wiring that directs AC power to one ormore electrical loads. Those of ordinary skill in the pertinent art willunderstand that the term “load” refers to an appliance, a switch, orsome other electrically powered device. Load terminals may also bereferred to as “feed-through” terminals because the wires connected tothese terminals may be coupled to a daisy-chained configuration ofreceptacles or switches. The load may ultimately be connected at the farend of this arrangement. The load terminals may also be connected to anelectrically conductive path that is also connected to a set ofreceptacle contacts. The receptacle contacts are in communication withreceptacle openings disposed on the face of the housing. Thisarrangement allows a user to insert an appliance plug into thereceptacle opening to thereby energize the device.

As noted above, there are several types of electric circuit protectiondevices. For example, such devices include ground fault circuitinterrupters (GFCIs), ground-fault equipment protectors (GFEPs), and arcfault circuit interrupters (AFCIs). This list includes representativeexamples and is not meant to be exhaustive. Some devices include bothGFCIs and AFCIs. As their names suggest, arc fault circuit interrupters(AFCIs), ground-fault equipment protectors (GFEPs) and ground faultcircuit interrupters (GFCIs) perform different functions. An arc faulttypically manifests itself as a high frequency current signal.Accordingly, an AFCI may be configured to detect various high frequencysignals and de-energize the electrical circuit in response thereto. Aground fault occurs when a current carrying (hot) conductor creates anunintended current path to ground. A differential current is createdbetween the hot/neutral conductors because some of the current flowingin the circuit is diverted into the unintended current path. Theunintended current path represents an electrical shock hazard. Groundfaults, as well as arc faults, may also result in fire. A “groundedneutral” is another type of ground fault. This type of fault may occurwhen the load neutral terminal, or a conductor connected to the loadneutral terminal, becomes grounded.

When a device is installed, its line terminals are connected to an ACpower source, such as a single phase 120 VAC AC power source. However,transient voltages may propagate in an electrical distribution system aswell as the AC power signal. Further, the amplitudes of transientvoltages are typically greater than the amplitude of the source voltageby at least an order of magnitude. Transient voltage pulses may begenerated by any number of events. For example, transient voltages maybe introduced into the distribution system by lightning. Transientvoltages may also be generated when an inductive load is turned off,when a motor with noisy brushes is operated, or by other such loadsituations.

Transient voltages are known to damage protective devices such that thedevice will cease to function as designed. This is sometimes referred toas an end of life condition. End of life failure modes include failureof device circuitry, the relay solenoid that opens the GFCI interruptingcontacts, and/or the solenoid driving device, such as a siliconcontrolled rectifier. The damage may result in the protective devicepermanently denying power to the protected portion of the electriccircuit. In this case, the user is forced to replace the protectivedevice. Alternatively, the damage may result in the protective devicestill providing power to the load even though the device has becomenon-protective. In this case, the user is left unprotected after anend-of-life condition has occurred. Thus the user is eitherinconvenienced by having to change out the device, or even worse, he isleft unprotected.

Most devices include surge protection components. However, surgeprotection components occupy a considerable volume within the devicehousing. As a result, the overall size of the device is relativelylarge, making it harder to install the device within a wall box. Anotherproblem is that surge protective components themselves are known toexperience an end-of-life condition. If the surge protection componentfails, the device is unprotected from damages due to transient voltages.

Accordingly, a compact protective device that includes an improvedspace-conserving surge protection arrangement is needed that continuesto afford protection after the occurrence of a voltage transient eventon the electrical distribution system. The compact protective devicemust be configured to reliably protect the user from a fault conditionin the electrical power distribution system. Further, a protectivedevice is needed that is equipped to decouple the load terminals fromthe line terminals in the event of an end of life condition.

SUMMARY OF THE INVENTION

The present invention addresses the needs described above by providing acompact protective device that includes an improved space-conservingsurge protection arrangement is needed that continues to affordprotection after the occurrence of a voltage transient event on theelectrical distribution system. The compact protective device of thepresent invention is configured to reliably protect the user from afault condition in the electrical power distribution system. Further,the protective device of the present invention is equipped to decouplethe load terminals from the line terminals in the event of an end oflife condition.

One aspect of the present invention is directed to an electrical wiringprotection device that includes a housing assembly having a plurality ofline terminals and a plurality of load terminals. A fault detectioncircuit is coupled to at least one of the plurality of line terminalsand configured to generate a fault detection signal in response todetecting at least one fault condition in the electrical distributionsystem. A circuit interrupter is coupled to the fault detection circuit,The circuit interrupter is configured to couple the plurality of lineterminals to the plurality of load terminals to form a conductiveelectrical path in a reset state, and decouple the plurality of lineterminals from the plurality of load terminals in response to a faultdetection signal in a tripped state. A voltage transient suppressioncircuit is coupled to at least one of the plurality of line terminals.The voltage transient suppression circuit is configured to generate asignal simulating the at least one fault condition in the event offailure.

In another aspect, the present invention includes an electrical wiringprotection device that includes a housing assembly including a pluralityof line terminals and a plurality of load terminals. A fault detectioncircuit is coupled to at least one of the plurality of line terminalsand configured to generate a fault detection signal in response todetecting at least one fault condition in the electrical distributionsystem. A circuit interrupter is coupled to the fault detection circuit.The circuit interrupter is configured to couple the plurality of lineterminals to the plurality of load terminals to form a conductiveelectrical path in a reset state, and decouple the plurality of lineterminals from the plurality of load terminals in response to a faultdetection signal in a tripped state. A voltage transient suppressioncircuit is coupled to at least one of the plurality of line terminals.The voltage transient suppression circuit includes an inductivecomponent coupled to at least one voltage transient suppression device.The inductive component is characterized by an inductive impedance thatis a function of frequency, whereby the inductive impedance is afunction of the frequency of a signal propagating in the voltagetransient suppression circuit.

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary of theinvention, and are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate various embodimentsof the invention, and together with the description serve to explain theprinciples and operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an electrical wiring device in accordancewith a first embodiment of the present invention;

FIG. 2 is a perspective view of a line spark gap structure in accordancewith one embodiment of the present invention;

FIG. 3 is a perspective view of a load spark gap structure in accordancewith another embodiment of the present invention;

FIG. 4 is a sectional view of the device depicted in FIG. 1;

FIG. 5 is a circuit diagram of a GFCI embodiment in accordance with thepresent invention; and

FIG. 6 is a partial schematic diagram of a protective device inaccordance with another embodiment of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to the present exemplaryembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.An exemplary embodiment of the wiring device of the present invention isshown in FIG. 1, and is designated generally throughout by referencenumeral 10.

As embodied herein, and depicted in FIG. 1, a block diagram of anelectrical wiring device 10 in accordance with a first embodiment of thepresent invention is disclosed. FIG. 1 is a general protection device inthat detector 40 may be configured as a GFCI detector, a GFEP detector,an AFCI detector or a combination thereof. In other words, the teachingsof the present invention are applicable to each type of protectivewiring device.

The protective device 10 includes neutral line terminals 20 and hot lineterminal 22 which are employed to connect device 10 to a source of ACpower, i.e., to the distribution wiring connected to the breaker panel.The electrical distribution system may distribute power using singlephase, split phase or multiple phase configurations by using two or moreconductors. The wiring device 10 shown in FIG. 1 is configured forsingle phase distribution. Device 10 also includes neutral load terminal24 and hot load terminal 26 that are used to connect device 10 to load28. Line terminals 20, 22 are coupled to load terminals 24, 26 by theinterruptible conductive path that includes neutral line conductor 12and hot line conductor 14. Neutral line conductor 12 and hot conductor14 pass through sensor assembly 32 and terminate at circuit interruptercontacts 50. The interruptible conductive path also includes neutralload conductor 16 and hot load conductor 18, which are connected to loadterminals 24, 26, respectively. A test circuit 400 is coupled betweenneutral line conductor 12 and hot load conductor 18.

During normal operations when no fault is present, the contacts 50 areclosed and AC power is provided to load 28 in the reset state. Generallyspeaking, sensor assembly 32 is coupled to fault detector 40. Faultdetector 40 is coupled to SCR 44. SCR 44 energizes the trip solenoid 46when it is in a conducting state. In turn, the trip solenoid 46 drivestrip mechanism 48. When trip mechanism 48 is activated, contacts 50 areopened. The device may be driven from the tripped state to the resetstate by pushing reset button 52.

If device 10 includes GFCI protection, sensor assembly 32 is configuredto sense the differential current flowing through the conductors 12, 14.When device 10 provides power to a load 28 under normal conditions, thedifferential current in the conductors 12, 14 is zero. In other words,the currents to and from the load are equal in magnitude and opposite inpolarity. However, when a ground fault (30) is present, a hot conductorin load 28 is coupled to ground. While the current through the hotconductor is sensed by sensor assembly 32, the return current isdiminished because the current flowing through the ground fault 30 flowsto ground instead of returning through sensor assembly 32. Thus, thedifferential current is not zero. If the differential current exceeds apredetermined amount, detector 40 provides a fault signal on detectoroutput line 41.

As those skilled in the art will recognize, differential transformer 34senses differential current via the magnetic field induced by thecurrent flowing through conductors 12, 14. In particular, conductors 12,14 pass through the aperture of a toroidal core 36. A non-zero current(differential current) in the conductors induces a magnetic flux in core36 to induce a signal in winding 38. Depending on the type of protectivedevice, sensor assembly 32 may include additional sensors (not shown)such as current transformers, shunts, voltage dividers, additionaltoroidal transformers and the like. Such sensors are chosen to sense thefault condition(s) of interest. Signal from winding 38 and from othersensors that may be included in the sensor assembly 32 are provided todetector 40.

As noted above, detector 40 determines whether the signal from sensorassembly 32 represents a fault condition. If a fault condition isdetected, detector 40 provides a signal to solid state switch 44 toenergize solenoid 46. Solenoid 46 in turn actuates trip mechanism 48 toopen circuit interrupting contacts 50. Interrupting contacts 50disconnect at least the hot load terminal 26 from the hot line terminal22, but may also serve to disconnect the neutral load terminal 24 fromneutral line terminal 20. Either way, device 10 is tripped.

Once device 10 trips, current stops flowing through the fault 30. Withpower to the fault removed, detector 40 can no longer provide a faultdetect signal to solid state switch 44. Solid state switch 44 turns offand solenoid 46 is de-energized. The interval of time between theinstant solenoid 46 energizes to trip the circuit interrupter, and thetime it de-energizes after the fault condition is successfullyeliminated, is typically less than 25 milliseconds. In the embodimentdepicted in FIG. 1, solenoid 46 is implemented using a miniaturizedconstruction because it does not have to be sized to withstand the heatthat would be generated if the solenoid were continuously energized.

As noted above, transient voltages are known to damage protectivedevices such that the device will cease to function as designed. Device10 may be protected from high voltage transients by connecting a metaloxide varistor (MOV) 54 across the line and/or load terminals to clampthe transient voltage to a predetermined threshold. Of course, thepredetermined voltage threshold is calculated such that device 10survives the transient event. However, when employing this means forproviding transient protection, MOV 54 must be relatively large in sizeto effectively clamp the transient voltage to an appropriate threshold.MOV 54 may be greater than 12 mm in diameter. As might be expected, a 12mm MOV is usually relatively costly.

Accordingly, one transient protection feature of the present inventionincludes the use of a MOV 56 in combination with an inductive component,such as solenoid 46. Voltage transients typically have an amplitude of 1to 6 kV. Because they are relatively brief in duration, they havefrequency components that may be greater than 100 kHz. On the otherhand, the impedance of solenoid 46 is typically greater than 500 Ohms ata frequency of 100 kHz. Thus, the frequency dependence of the coilimpedance may be used to safeguard MOV 56. Accordingly, MOV 56 may bedownsized to take advantage of the frequency dependence of the coilimpedance. In other words, MOV 56 may have a diameter that is less thanor equal to 7 mm, while still managing to clamp the voltage at anappropriate threshold, because the solenoid impedance limits the amountof current through MOV 56. This approach may also provide cost benefitsas well. A smaller MOV is relatively inexpensive when compared to alarger MOV. Further, the life expectancy of MOV 56 may be greatlyincreased by the impedance of solenoid 46 because it restricts theamount of current through the MOV for a given voltage transientmagnitude. However, it is still possible for MOV 56 to experience anend-of-life condition.

An end-of-life condition may occur if the magnitude of the voltagetransient is large enough. An end-of-life condition may also occur ifthere is a large number of voltage transients. Environmental stressesmay also play a part in causing a failure. Whatever the cause, atend-of-life, a MOV becomes increasingly resistive in nature. If theresistance of MOV 56 is less than about 100 Ohms, solenoid 46 issufficiently coupled to the power source to actuate trip mechanism 48 toopen interrupting contacts 50. The current flowing through theresistance of MOV 56 would also be conducted through solenoid 46. Thecurrent, if uninterrupted, would cause solenoid 46 to burn out.

The present invention includes an auxiliary switch mechanism to avoidsolenoid burn-out. An auxiliary switch 58 is disposed in series withsolenoid 46. Auxiliary switch 58 is coupled to the trip mechanism 48, oralternatively, to the interrupting contacts 50 such that the contacts ofauxiliary switch 58 open when the circuit interrupter is in the trippedcondition. Device 10 may be reset by manually actuating reset button 52.This also results in the contacts of auxiliary switch 58 being closed.Upon reset, solenoid 46 is again coupled to the power source by way ofthe resistance of MOV 56, and again, trip mechanism 48 opens contacts 50as well as the contacts of auxiliary switch 58. In sum, when MOV 56 hasreached end-of-life, solenoid 46 is only momentarily energized. Solenoid46 actuates the trip mechanism each time a reset action attempt isrepeated. Even though MOV 56 has experienced an end-of-life condition,device 10 maintains its protective functionality. There is one caveat,however.

If the end-of-life resistance of MOV 56 is greater than 100 Ohms,solenoid 46 may not be sufficiently coupled to the voltage source totrip the interrupting mechanism 48. If the interrupting mechanism doesnot trip, the current through solenoid 46 will not be interrupted byauxiliary switch 58. The uninterrupted current through solenoid 46 mightcause the solenoid to burn out.

Referring to dashed line 101, in an alternate embodiment MOV 100 may beincluded to protect device 10 from a high voltage transients. Unlike MOV56, MOV 100 prevents solenoid burn-out for all end-of-life resistancevalues. Note that MOV 100 is connected in series with solenoid 46. Thus,it is protected by the impedance of solenoid 46 in a similar manner towhat has been described for MOV 56. However, because of the seriescombination of MOV 100 and solenoid 46, the current flowing through theseries combination creates a differential current in the conductorspassing through differential transformer 34. Detector 40 responds to thedifferential current and causes the device to trip in the mannerpreviously described. The predetermined threshold for a GFCI istypically 6 mA, and for a GFEP or AFCI is typically 30 mA. Should theend-of-life resistance of MOV 100 generate a current greater than thedetection threshold in detector 40, device 10 will trip and auxiliaryswitch 58 will open to protect solenoid 46 from burnout.

Of course, if the current flowing through the series combination of MOV100 and solenoid 46 are less than the detection threshold, device 10will not trip. However, solenoid 46 is configured to be able towithstand the continuous flow of current of this magnitude. By way ofillustration, if MOV 100 has a resistance that is less than about 4,000Ohms, a device having a 30 mA detection threshold will trip, because thecurrent generated will be greater than the threshold. On the other hand,as MOV 100 becomes more resistive, i.e., the resistance becomes greaterthan about 4,000 Ohms, the current generated is less than thedifferential current threshold and device 10 will not trip. However,solenoid 46 is configured to withstand current that is less than thedetection threshold. Accordingly, solenoid 46 will not burn out ineither scenario because the voltage transient circuit is coupled to thefault detector and generates a differential current which in turn causesthe protective device to trip. The protective device of the presentinvention is both safe and reliable in the face of an end-of-lifecondition.

Another feature of the present invention relates to preventing device 10from being tripped by brief signals from sensor 32 that arise duringvoltage transient events. In particular, low pass filter 102 may bedisposed between detector output 41 and SCR 44. Filter 102 is configuredto filter out the momentary currents that flow through MOV 100 toprevent solid state switch 44 from responding to voltage transientevents. As a result, trip mechanism 48 is not nuisance-actuated by thesevoltage transient events. In an alternative embodiment, low pass filter102 may be implemented in detector 40 to avoid using discretecomponents.

Another feature of the present invention provides spark gaps (200, 300)for the absorption of the energy from the most severe transients. Forexample, voltage transients due to lightning have been known to produce10 kV and/or 10 kA. The spark gaps are disposed in device 10 such thatthe surge current passing through the spark gap does not generate anoutput signal from sensor assembly 32. In other words, the spark gap(s)200, 300 are configured such that the discharge current is notmanifested as a differential current that may possibly be sensed bytransformer 34. Spark gaps 200, 300 allow protective device 10 to remainin an operational condition in the presence of extremely severe voltagetransients, or the currents that result from such voltage transients.

Referring to FIG. 2, a perspective view of device 10 is shown thatillustrates a spark gap structure 200 in accordance with the presentinvention. Spark gap structure 200 is disposed between the lineterminals 20, 22, and under sensor assembly 32. The contact assembly 50is implemented by movable contacts 206, 208 and fixed contacts 210, 212.In particular, cantilever member 202 is connected to line neutralterminal 20 and cantilever member 204 is connected to line hot terminal22. Movable contacts 206, 208 are disposed at the distal ends ofcantilever beams 202, 204, respectively. Load terminals 24, 26 areelectrically connected to fixed contacts 210, 212. Trip mechanism 48 isconfigured to move contact pairs (206, 210) and (208, 212) intoelectrical connection when device 10 is reset and to move them out ofelectrical connection when device 10 is tripped.

Spark gap structure 200 is an electrically conductive member disposedbetween cantilever beams 202, 204. Air gap 214 is disposed betweencantilever 204 and one end of the spark gap structure 200, whereas airgap 216 is disposed between cantilever 202 and the other end of thespark gap structure 200. The sum of gaps 214, 216 are typically between0.030 and 0.060 inches. The gap structure 200 may be implemented suchthat the two gaps may be unequal. Further, one of the air gaps may beeliminated. Finally, an insulating material that bridges the gaps may beincluded, the length of the insulating material being at least typically0.250 inches in length.

As shown in FIG. 1, a second air gap structure 300 may be disposedbetween the load conductors 16, 18. Referring to FIG. 3, a perspectiveview of the load spark gap structure 300 is disclosed. Spark gapstructure 300 is disposed between conductors 16, 18 that connect theload terminals 24, 26 to fixed contacts 210, 212. Spark gap structure300 is also configured to absorb the energy generated by a severevoltage transient event.

The present invention contemplates using any type of suitable structureto implement interrupting contacts 50. Reference is made to U.S. patentapplication Ser. No. 10/900,769, filed Jul. 28, 2004, which isincorporated herein by reference as though fully set forth in itsentirety, for a more detailed explanation of the various types ofcircuit interrupting structures that may be employed to implement thepresent invention.

FIG. 4 is a partial sectional view of a device 10 that shows testcircuit 400 and test button 402. Contacts 404 are normally open. Using aGFCI as an example, test circuit 400 couples the hot load terminal 26 toneutral line terminal 20 when test button 402 is depressed (See alsoFIG. 1 for a schematic representation). The resulting current throughtest circuit 400 is sensed by differential transformer 34 in the samemanner as a true ground fault condition. The gap between open contacts404 is required to be greater than a predetermined spacing to preventthe test circuit 400 from becoming damaged during a voltage transientevent. The predetermined gap is approximately 0.100 inches. However, anyrequirement that would necessitate test button 402 to travel 0.100inches to close the gap would not be ergonomic. Accordingly, the gapbetween test button 402 and contacts 404 may be reduced by providinggaps 406 and 408. Note that the MOVs (56, 100) and the air gapstructures (200, 300) provide the test circuit 400 with transientprotection.

In another embodiment, test circuit 400 may also be configured toprovide automatic testing of device 10. Reference is made to U.S. Pat.No. 6,674,289 and U.S. patent application Ser. No. 10/668,654 which areincorporated herein by reference as though fully set forth in itsentirety, for a more detailed explanation of the automatic test circuit400.

Referring to FIG. 5, a circuit diagram of a GFCI embodiment 10′ isshown. Device 10′ includes feed-through terminals 501 configured toconnect device 10′ to the wiring that provides power to downstreamreceptacles. Device 10′ also includes receptacle load terminals 502 thatare configured to accept a plug from a user attachable load.Interrupting contacts 505 are configured to disconnect the feed-throughterminals 501 from the load terminals 502 when device 10′ is in thetripped condition.

Indication components are included to alert the user to the reset ortripped status of device 10′. Indication components may include visualindicators, audible indicators, or both. Such indicators are configuredto emit a steady indication or, alternatively, may emit an intermittentindication such as visual flashing or audible beeping. In particular,device 10′ provides an indicator 506 that is coupled in parallel withauxiliary switch 58. Referring to the schematic diagram, indicator 506emits a signal when device 10′ is connected to an AC power source andtripped. Indicator 508 may be coupled in series with auxiliary switch58. Indicator 508 emits a signal when device 10′ is connected to asource of power and is reset. Indicator 506 and indicator 508 may beused in combination or separately. Note that MOV 100 (or 56) limits theamplitude of the voltage transient that could otherwise create anend-of-life condition in the auxiliary switch 58, or in the indicators506, 508.

Referring to FIG. 6, a partial schematic diagram of a device inaccordance with another embodiment of the present invention is shown. Inthis embodiment, MOV 600 is connected across the load terminals 24, 26.MOV 600 is coupled to differential transformer 34 so as to generate adifferential current when an end-of-life condition occurs. Transformer34 is coupled to the load side of device 10. In the manner previouslydescribed, the differential current is detected by detector 40. In turn,detector 40 provides a signal to solid state switch 44 to energizesolenoid 46. Trip mechanism 48 is activated in response thereto, openinginterrupting contacts 50. Accordingly, an end-of-life condition in MOV600 is interrupted before MOV 600 is able to overheat. The interruptionof the current is accomplished by interrupting contacts 50. MOV 56 andMOV 100 may be coupled to the line terminals 20, 22 by way of solenoid46 in the manner previously described.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus, itis intended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. An electrical wiring protection device comprising: a housing assemblyincluding a plurality of line terminals and a plurality of loadterminals, the plurality of line terminals being configured to becoupled to a source of AC power; a fault detection circuit including apower supply coupled to at least one of the plurality of line terminalsand configured to generate a fault detection signal in response todetecting at least one fault condition in the electrical distributionsystem; a circuit interrupter coupled to the fault detection circuit,the circuit interrupter being configured to couple the plurality of lineterminals to the plurality of load terminals to form a conductiveelectrical path in a reset state, and decouple the plurality of lineterminals from the plurality of load terminals in response to a faultdetection signal in a tripped state; and a voltage transient suppressioncircuit coupled to the plurality of line terminals and the power supply,the voltage transient suppression circuit generating a leakage currentin the event of a voltage transient suppression circuit failure, theleakage current simulating the at least one fault condition, the voltagetransient suppression circuit also being configured to decouple thepower supply from the source of AC power in the tripped state.
 2. Thedevice of claim 1, wherein the fault detection circuit is configured togenerate a fault detection signal in response to the voltage transientsuppression circuit experiencing an end-of-life condition.
 3. The deviceof claim 1, wherein the circuit interrupter is configured to decouplethe plurality of line terminals from the plurality of load terminals inresponse to the voltage transient suppression circuit experiencing anend-of-life condition.
 4. The device of claim 1, wherein the voltagetransient suppression circuit includes an inductive component coupled toat least one voltage transient suppression device, the inductivecomponent being characterized by an inductive impedance that is afunction of frequency, whereby the inductive impedance is a function ofthe frequency of a signal propagating in the voltage transientsuppression circuit.
 5. The device of claim 4, wherein the voltagetransient suppression circuit includes at least one metal oxide varistor(MOV) in series with the inductive component.
 6. The device of claim 4,wherein the inductive component includes a solenoid configured toactuate the circuit interrupter in response to the fault detectionsignal.
 7. The device of claim 6, wherein the voltage transientsuppression circuit includes an auxiliary switch configured as part ofthe circuit interrupter, the auxiliary switch being coupled between aline terminal and a portion of the voltage transient suppressioncircuit, the auxiliary switch decoupling the voltage transientsuppression circuit from one of the plurality of line terminals when thecircuit interrupter is in the tripped state.
 8. The device of claim 7,wherein the voltage transient suppression device includes the at leastone MOV coupled in series between the solenoid and a line terminal. 9.The device of claim 8, wherein the at least one MOV includes a first MOVdisposed in parallel with a second MOV.
 10. The device of claim 1,wherein the circuit interrupter further comprises: a switching elementcoupled to the fault detection circuit, the switching element beingturned ON in response to the fault detection signal; a solenoid coupledto the switching element, the solenoid being energized in response tothe switching element being in the ON state; and at least four sets ofinterrupting contacts disposed between the plurality of line terminalsand the plurality of load terminals and operatively coupled to thesolenoid, the at least four sets of interrupting contacts beingconfigured to decouple the plurality of line terminals from theplurality of load terminals in response to the solenoid being energized.11. The device of claim 10, wherein the voltage transient suppressioncircuit includes a MOV coupled to a line terminal by way of thesolenoid.
 12. The device of claim 11, wherein the voltage transientsuppression circuit includes an auxiliary switch coupled between a lineterminal and the solenoid, the auxiliary switch being configured as partof the circuit interrupter, the voltage transient suppression circuitfurther including at least one indicator coupled to the auxiliaryswitch.
 13. The device of claim 12, wherein the voltage transientsuppression circuit is configured to protect the at least one indicatorfrom a voltage transient event.
 14. The device of claim 12, wherein theat least one indicator includes a trip indicator.
 15. The device ofclaim 12, wherein the at least one indicator includes a reset indicator.16. The device of claim 12, wherein the at least one indicator includesan audio indicator and/or a visual indicator.
 17. The device of claim 1,wherein the voltage transient suppression circuit includes a MOVdisposed between the plurality of line terminals.
 18. The device ofclaim 1, wherein the voltage transient suppression circuit includes aMOV disposed between the plurality of load terminals.
 19. The device ofclaim 1, wherein the voltage transient suppression circuit furtherincludes a spark gap structure coupled between the plurality of lineterminals.
 20. The device of claim 1, wherein the voltage transientsuppression circuit further includes a spark gap structure coupledbetween the plurality of load terminals.
 21. The device of claim 1,wherein the fault detection circuit includes a differential transformerthat senses an end-of-life signal generated by the voltage transientsuppression circuit.
 22. The device of claim 1, further comprising atest circuit coupled to the fault detection circuit, the test circuitbeing configured to generate a test signal that simulates the at leastone fault condition.
 23. The device of claim 22, wherein the testcircuit includes a test switch configured to generate the test signalwhen the switch is in the closed position.
 24. The device of claim 22,wherein the test switch includes an open position that includes two airgaps.
 25. The device of claim 22, wherein the test circuit automaticallygenerates the test signal.
 26. The device of claim 1, wherein the atleast one fault condition includes an arc fault condition.
 27. Thedevice of claim 1, wherein the at least one fault condition includes aground fault condition.
 28. An electrical wiring protection devicecomprising: a housing assembly including a plurality of line terminalsand a plurality of load terminals, the plurality of line terminals beingconfigured to be coupled to a source of AC power; a fault detectioncircuit including a power supply coupled to the plurality of lineterminals and configured to generate a fault detection signal inresponse to detecting at least one fault condition in the electricaldistribution system; a circuit interrupter coupled to the faultdetection circuit, the circuit interrupter being configured to couplethe plurality of line terminals to the plurality of load terminals toform a conductive electrical path in a reset state, and decouple theplurality of line terminals from the plurality of load terminals inresponse to a fault detection signal in a tripped state; and a voltagetransient suppression circuit coupled to the plurality of line terminalsand the power supply, the voltage transient suppression circuitincluding an inductive component coupled to at least one voltagetransient suppression device, the inductive component beingcharacterized by an inductive impedance that is a function of frequency,whereby the inductive impedance increases if the frequency of a signalpropagating in the voltage transient suppression circuit increases, thevoltage transient suppression circuit generating a leakage current inthe event of a voltage transient suppression circuit failure, theleakage current simulating the at least one fault condition, the voltagetransient suppression circuit also being configured to decouple thepower supply from the source of AC power in the tripped state.
 29. Thedevice of claim 28, wherein the voltage transient suppression deviceincludes at least one metal oxide varistor (MOV) in series with theinductive component.
 30. The device of claim 28, wherein the inductivecomponent includes a solenoid configured to actuate the circuitinterrupter in response to the fault detection signal.
 31. The device ofclaim 28, wherein the voltage transient suppression circuit includes anauxiliary switch configured as part of the circuit interrupter, theauxiliary switch decoupling the voltage transient suppression circuitfrom one of the plurality of line terminals when the circuit interrupteris in the tripped state.
 32. The device of claim 31, wherein the voltagetransient suppression device includes at least one MOV coupled in seriesbetween the solenoid and a line terminal.
 33. The device of claim 32,wherein the at least one MOV includes a first MOV disposed in parallelwith a second MOV.
 34. The device of claim 28, wherein the voltagetransient suppression circuit includes a MOV disposed between theplurality of line terminals.
 35. The device of claim 28, wherein thevoltage transient suppression circuit includes a MOV disposed betweenthe plurality of load terminals.
 36. The device of claim 28, wherein thevoltage transient suppression circuit further includes a spark gapstructure coupled between the plurality of line terminals.
 37. Thedevice of claim 28, wherein the voltage transient suppression circuitfurther includes a spark gap structure coupled between the plurality ofload terminals.
 38. An electrical wiring protection device comprising: ahousing assembly including a plurality of AC power terminals, theplurality of AC power terminals including a plurality of line terminals,a plurality of load terminals, and a plurality of receptacle loadterminals, the plurality of line terminals being configured to becoupled to a source of AC power; a fault detection assembly coupled toat least one of the plurality of line terminals and configured togenerate a fault detection signal in response to detecting at least onefault condition in an electrical distribution system; a voltagetransient suppression circuit coupled to selected ones of the pluralityof AC power terminals, the voltage transient suppression circuitgenerating a leakage current in the event of a voltage transientsuppression circuit failure, the leakage current simulating the at leastone fault condition; and a circuit interrupter coupled to the faultdetection assembly and the voltage transient suppression circuit, thecircuit interrupter including at least four sets of interruptingcontacts configured to couple the plurality of AC power terminals in areset state, and decouple the plurality of AC power terminals in atripped state, the circuit interrupter being responsive to the faultdetection signal such that the at least four sets of interruptingcontacts are driven from the reset state to the tripped state such thatat least a portion of the voltage transient suppression circuit is alsointerrupted in the tripped state.
 39. The device of claim 38, whereinthe voltage transient suppression circuit includes an inductivecomponent coupled to at least one voltage transient suppression device,the inductive component being characterized by an inductive impedancethat is a function of frequency, whereby the inductive impedance is afunction of the frequency of a signal propagating in the voltagetransient suppression circuit.
 40. The device of claim 39, wherein theat least one voltage transient suppression device includes at least onemetal oxide varistor (MOV) in series with the inductive component. 41.The device of claim 40, wherein the at least one MOV includes a firstMOV disposed in parallel with a second MOV.
 42. The device of claim 39,wherein the inductive component is a solenoid disposed the faultdetection assembly and the at least four sets of interrupting contactsinclude an auxiliary switch coupled to the solenoid, the auxiliaryswitch being configured to interrupt the at least a portion of thevoltage transient suppression circuit in the tripped state.
 43. Thedevice of claim 42, wherein the auxiliary switch is coupled between oneof the plurality of line terminals and the solenoid.
 44. The device ofclaim 38, wherein the at least four sets of interrupting contactsincludes an auxiliary switch coupled between the plurality of lineterminals, the auxiliary switch being configured to interrupt the atleast a portion of the voltage transient suppression circuit in thetripped state.
 45. The device of claim 44, wherein the voltage transientsuppression circuit includes at least one indicator coupled to theauxiliary switch, a portion of the voltage transient suppression circuitis configured to protect the at least one indicator from a voltagetransient event.
 46. The device of claim 45, wherein the at least oneindicator includes a trip indicator or a reset indicator.
 47. The deviceof claim 38, wherein the voltage transient suppression circuit furtherincludes a spark gap structure coupled between the plurality of lineterminals or the plurality of load terminals.
 48. The device of claim38, wherein the fault detection assembly includes a power supply coupledto the plurality of line terminals, and wherein the at least a portionof the voltage transient suppression circuit that is interrupted in thetripped state decouples the power supply from the source of AC power inthe tripped state.
 49. The device of claim 48, wherein the at least foursets of interrupting contacts include an auxiliary switch that isconfigured to decouple the power supply from the source of AC power inthe tripped state.